DE2308637A1 - PROCESS FOR MANUFACTURING LONG DISTANCE GOODS, IN PARTICULAR ELECTRICAL CABLES AND LINES - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT 8520 Erlangen,

Berlin and Munich Werner-von-Siemens-Str. 50

Our
VPA 1 cm / win

Process for the production of elongated goods, in particular electrical cables and wires

The increasing demand for electrical energy requires powerful Distribution networks ahead. For this purpose, one is looking for a higher load capacity with the lowest possible loss of transmission links interested and therefore endeavors to provide insulation for electrical cables and lines with the highest possible heat resistance and to use the lowest possible dielectric losses. This means for electrical cables with a plastic insulation that insulation is based on the previously common thermoplastics, such as polyvinyl chloride and polyethylene, to an increasing extent More heat resistant insulation, for example based on crosslinked polyethylene, must be replaced.

In other technical fields, too, there is an interest in finding, if possible, continuously shaped, possibly thermally stable to be able to use profiles or pipes made of a plastic located on a carrier, for example when transporting hot water or hot oils, when using profiled sealing tapes and cords, as well as when Use of metal strips or metal strands that are coated with a plastic, for example for corrosion protection purposes are.

For the production of electrical cables with an insulation made of a crosslinked plastic, for example a crosslinked one Polyethylene, a process is known in which the polyethylene is applied to the conductor in the uncrosslinked state and then by high-energy radiation that causes cross-linking or cross-linking in

409836/0939

a tougher and more elastic state is converted (DT-AS 1 000 076). However, such a method is procedural very complex and associated with considerable costs. In technology there has therefore been a different drive, in which the initially thermoplastic material is chemically crosslinked. To do this will be chemical crosslinking agents, preferably organic peroxides, used in the thermoplastic polyethylene blend are incorporated and which disintegrate at elevated temperatures and thereby the chemical crosslinking of the polyethylene cause (DT-PS 1 109 366). The peroxides used so far preferably for crosslinking polyethylene, in particular the ditertiary alkyl or aralkyl peroxides such as di-dl-cumyl peroxide, however, have the property when thermal decay, especially in the temperature range of technical interest, gaseous and volatile peroxide reaction products split off, which lead to gas bubbles in the crosslinked polyethylene.

To prevent this pore formation, which is particularly disadvantageous for electrical purposes, it is customary to crosslink the polyethylene insulation of electrical cables at high pressure, in particular under tensioned water vapor at pressures of about 160 to 200 N / cm ² (16 to 20 atmospheres) (DT- OS 1 915 892). The hereby achievable crosslinking temperatures are due to the high water vapor pressure at a maximum of about 210 ⁰ C. Therefore, the process amount in the continuous carrying out by means of superheated V / asserdampf filled Vulkanisierrohren through which run coming from the extruder sheathed conductor, the residence times of the coated Depending on the insulation material (compound structure) and insulation wall thickness, conductors take about 1 to several minutes. Since the vulcanizing tubes cannot be made arbitrarily long, the throughput speed of the covered conductors must be adapted to this dwell time. The throughput speed is included

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much smaller than that used in the extrusion of the conductor sheaths attainable speeds.

The vulcanization of cable insulation made from synthetic or natural rubbers is also known To be carried out "without pressure", i.e. at or approximately at atmospheric pressure, in a salt bath (GB-PS 906 139 and 1 012 562, DT-OS 1 939 134). By suitably building up the rubber compounds, for example by using sulfur crosslinking Ren instead of peroxides, a bite-free vulcanizate can be achieved.

The invention is based on the object for the production of elongated material such as shaped, if necessary Profiles or pipes located in a carrier on the basis of cross-linked polyethylene, in particular for the production of electrical cables and wires with a sheath and / or insulation based on a cross-linked polyethylene, one that is more economical and more favorable from a technical point of view than the known crosslinking with pressurized steam To create a process that at the same time has good electrical properties, in particular good dielectric properties, the profiles or pipes, in particular the casing and / or insulation, guaranteed. Here are under "wrapping and / or insulation "understood layers on the basis of cross-linked polyethylene provided within the cable cross-section, which are, for example, low-conductivity conductor cover layers or insulation that is directly on a conductor or applied to a conductor coated with a conductor smoothing v / ground, or around cable sheaths or can act as a protective layer of a metal cable jacket.

To solve this problem, the invention is based on a method in which the polyethylene in the uncrosslinked state extruded and then under the action of heat in the presence is crosslinked by organic radical formers. According to

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3/7532

According to the invention, a polyethylene mixture is used to produce the profiles or pipes, in particular for sheathing and / or insulating electrical cables or lines, which contains 0.1 to 20% by weight, based on the polymer, of a crosslinking-reinforcing coagent based on of 2,4-dienoxy-6-aminoalkyl (en) -s-triazines and / or of N, N ^! -Bis- (2.4-dienoxys-trlazin-6) -diamines contains; This polyethylene mixture is after extrusion in by heating in a heating section, for example a salt bath, a liquid bath, a fluidized bed or in hot air or in a suitably heated inert gas such as nitrogen, argon, carbon dioxide, etc. at or approximately at atmospheric pressure and at one temperature of over 150 °
networked.

temperature of over 150 ⁰ C, preferably of at least 200 ⁰ C, continuous

In the method designed according to the invention, the crosslinking of the existing ones based on a polyethylene takes place Profiles and tubes, in particular the sheathing or insulation of an electrical conductor or an electrical one Cable, under normal pressure conditions, i.e. without overpressure. This makes it possible to do what is generally referred to as "pressureless" Crosslinking to be carried out at significantly higher temperatures and therefore at a significantly greater speed. this is surprising insofar as it has previously been assumed that polyethylene cannot be depressurized with the aid of organic radical formers can be crosslinked if you consider the appearance of gas bubbles in crosslinking as a result of the formation of gaseous cleavage products, the radical generator wants to prevent. The invention is therefore based essentially on the knowledge that the crosslinking of polyethylene with the help of organic radical formers The gaseous fission products formed during the pressureless crosslinking then do not lead to the formation of bubbles. . _ . ... lead if you can

Polyethylene adds certain crosslinking-enhancing additives.

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Such only when using networking reinforcing additives occurs at crosslinking temperatures of over 200 ° C, especially at temperatures above 220 ⁰ C, so at temperatures that are not hardly achieved in the conventional crosslinking of polyethylene under pressurized steam or no blistering. Such blistering, however, can usually not be avoided at crosslinking temperatures above 220 ° C if no crosslinking-reinforcing additives are added to the polyethylene or if only those crosslinking-reinforcing additives are added to the polyethylene, as they are previously known. Such a known networking-boosting additive, for example, which can interfere poor due to its inadequate solubility in polyethylene and because of the low melting point of about 27 ° C in polyethylene and distribute cyanurate (TAC) and at especially at high curing temperatures (> 22O ⁰ C) Evaporation losses and thus impairment of specified mixing ratios.

Since - as already mentioned - the networking temperature at the new processes can be significantly above that of the previously customary processes, the crosslinking can be significantly greater carried out in a shorter time and thus with a significantly higher production speed. The throughput speed When networking, the extrasion speeds possible without the use of unusually long heating zones of the polyethylene are approximated, so that the necessary for crosslinking organic during the extrusion Free radical formers already containing polyethylene mixture and the subsequent crosslinking in the same operation more economical utilization of the respective extruder results.

The crosslinking temperature in the pressureless crosslinking provided in the context of the invention has upper limits set. The outermost limit is determined by the decomposition temperature

409836/0939

door of the polyethylene, which is about 400 ⁰ C, is formed. Otherwise, however, crosslinking ^{temperatures of over 300 °} C. are less suitable. In this temperature range, the actual crosslinking reaction takes place in less than 1 second. The corresponding throughput times, ie the actual crosslinking times increased by the heating time of the polyethylene to the crosslinking temperature, of the insulated or sheathed cable or the line through the salt bath, then no longer play a significant role in the production process. The temperature range for the cross-linking of the polyethylene-after, according to the invention is therefore formed method in increasing the production rate at 210 to 300 ⁰ C, preferably at about 230 to 280 ⁰ C.

Another advantage of the new process, in which the organic radical formers required for the crosslinking and the crosslinking-enhancing coagents already contained Polyethylene is extruded and crosslinked without pressure in the same operation, can be seen in the fact that now at the • Manufacture of electrical cables and wires, including polyethylene insulation Electrical conductors with a non-circular cross-section, for example so-called sector conductors, in particular also pre-twisted Sector manager, can be networked in the same work step. Insulations on such conductors are made of one thermoplastic material is usually applied in the so-called hose stretching process, in which the conductor first at a distance surrounding hose is pressed and in which the conductor at a greater speed than the Exit speed of the hose is withdrawn so that the hose by stretching to rest on all sides Head is brought. The use of this hose stretching process with subsequent crosslinking of the thermoplastic Plastic in the vulcanizing tube filled with saturated steam was previously not feasible because it made it pore-free Crosslinking the required pressure in the vulcanizing tube

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- 7 - the hose was compressed too early.

The main advantage of the new method, therefore, is that in spite of pressureless cross-linking of the polyethylene at cross-linking temperatures of preferably about 220 ⁰ C a non-porous and electrically quality product, in particular an insulation or sheathing of electric cables obtained. The products of crosslinked polyethylene obtained by this process therefore contain no bubbles or vacuoles due to gaseous decomposition products of the peroxidic crosslinking agent used or to other causes. Their mechanical and electrical properties are therefore at least equivalent to the products obtained with pressurized steam.

The measure of pressureless crosslinking of the polyethylene provided in the context of the invention is essentially based on the use of certain crosslinking-enhancing co-agents, i.e. the 2,4-dienoxy-6-amino-alkyl (en) -s-triazines and / or of the N, N'-bis- (2,4-dienoxy-s-triazine-6) -diamines, in which it are special, unsaturated derivatives of s-triazine. The production of these substances takes place on a very preparative basis simple way by aminolysis of trisenoxy-s-triazines with Diaminoalkanes, diaminoalkylenes, diaminoalkylated aromatics and heterocycles or by / aminolysis of trisalkenoxy-s-triazines with primary aliphatic amines and secondary alkylene amines. These manufacturing processes are the subject of patent applications P (VPA 73/7526) and

P (VPA 73/7529). The mentioned networking

Strengthening coagents are used in an amount of 0.1 to 20% by weight, preferably 0.1 to 5% by weight , based on the polymer.

The mentioned 2,4-dienoxy-6-alkyl (en) amino-s-trlazine are by the general formula

409836/0939

- β - VPA vüMM. 73/7532

OR

shown in which

R is an allyl, methallyl, ethallyl, propallyl, 3-ethylbutenyl-2-, 3-butenyl, 2,4-hexadienyl, crotyl, 3-nonenyl group

R «. = R, but the groups described under R can also be in various combinations to R ₁

R _{2 is} an alkyl group with 1 to 20 carbon atoms, an alkylene cycloalkane group with 4 to 10 carbon atoms,

an alkylenaryl (heteroaryl) group with 7 to 10 carbon atoms,

an allyl, alkene and alkyne group of 3 to 16 carbon atoms mean and

R ₃ = hydrogen or an alkylene group which _{can be linked cyclically to R 2} , it being possible for individual methylene groups to be substituted by oxo or thio groups.

Examples of the alkyl groups are methyl, ethyl, propyl, butyl, hexyl, stearyl groups and isomers in which the Amino group is connected to the alkyl radical via a methylene group.

Examples of alkylene-cycloalkane groups are methylenecyclopropane, Ethylenecyclobutane, ethylenecyclohexane groups. The alkylenearyl groups can be benzyl, phenethyl-cinnamyl groups. Alkene and alkyne groups can be, for example, butenyl-3-, hexenyl-4- and butynyl-3 or heptynyl-5 groups. An alkylene group can be a trimethylene or tetramethylene group, with oxo or thio groups instead of methylene groups

can be built in.

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409836/0939

Examples of unsaturated alkyl (-en) amino-s-triazine esters are:

2,4-dialloxy-6-methylamino-s-triazine (R = R ₁ = allyl, R ₂ = methyl, R ₃ = H)

2,4-diethalloxy-6-stearylamino-s-triazine (R = R ₁ = ethallyl, R ₂ '= stearyl, R ₃ = H)

2,4-dimethalloxy-6-allylamino-s-triazine (R = R ₁ = methallyl, R ₂ = allyl, R ₃ = H)

2,4-dialloxy-6-phenethylamino-s-triazine (R = R ₁ = allyl, R ₂ = phenethyl, R ₃ = H)

2,4-dialloxy-6-pyrrolidino-s-triazine (R = R ₁ = allyl, R ₃ -R ₃ ⁼ tetramethylene)

2,4-dimethalloxy-6-pyrrolino-s-triazine (R = R ₁ = methallyl, R ₃ -R ₃ = 1,4-butene- (2))

2,4-dialloxy-6-morpholino-s-triazine (R = R ₁ ts allyl, R ₃ -R ₃ = ethylene oxoethylene)

2, ^ Dicrotyloxy-e-benzylamino-s-triazine (R = R ₁ a crotyl, R ₂ = benzyl, R ₃ = H)

The preparation process for these unsaturated s-triazines is surprisingly simple: trisenoxy-s-triazine and alkyl (-en) amine and arylalkylamine, respectively, are melted and combined. After standing for several hours, the unsaturated alkyl (- en) aminotriazine ester precipitates mostly as a solid in approx. 80 90% yield.

The "bridged" unsaturated s-triazines mentioned, that is to say the N, N'-bis (2,4-dienoxy-s ~ triazine-6) diamines, are replaced by the Formula: _ 10 -

4 0.9 836/0939

shown in which

R is an alkylene group with 2 to 18 carbon atoms, a bisalkylenecycloalkane group with 5-10 carbon atoms,

or dialkylenefuran, thiophene, pyridine or triazine group with 6 to 12 carbon atoms and other heterocycles which are polysubstituted by alkylene groups,

R _{1 is} preferably allyl, but also crotyl, methallyl-ethallyl, propallyl, 3-butenyl, 2-hexenyl, 2,4-hexadienyl-3-decenyl and other unsaturated groups and

R2 = H or an alkylene group, which together with R forms a diazacycloaliphatic ring.

Examples of alkylene groups are: ethylene, 2-methylpropylene-1,3-f 2,3-dimethylbutylene-1,4, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene groups and homologues with methyl -, ethyl and isopropyl groups in the side chain and 2 methylenamino groups in the cu _f «^ position.

Examples of bisalkylene-cycloalkane groups are bismethylene cyclopropane, Bismethylene or bisethylene cyclobutane, bismethylene or bisethylene cyclohexane.

Bisalkylenarylene groups are, for example, bisraethylene or Bisethylene-phenylene, -tolylene, -naphthylene groups. Dialkylenfuran, thiophene, pyridine and triazine groups are diethylenefuran, thiophene, pyridine and triazine groups.

409836/0939

The following are some examples of these N, N'-bis (2,4-dienoxy-s-triazine-6) diamines given:

N, N'-bis (2,4-dialloxy-s-triazine-6) -diaminoethane (R = ethylene, R ₁ = allyl, R ₂ = H)

N, N'-bis (2,4-dialloxy-s-triazine-6) -diaminobutane (R = tetramethylene = allyl, R ₂ = H)

N, N'-bis (2,4-dimethalloxy-s-triazine-6) -diaminohexane (R = hexamethylene, R ₁ = methallyl, R ₂ = H)

N, N'-bis (2,4-diethalloxy-s-trlazin-6) -diaminooctane (R = octamethylene, R ₁ = ethallyl, R ₂ = H)

N, N'-bis (2,4-dialloxy-s-triazine-6) -diaminodiethylen-2,4-s-

triazine
(R = 2,4-diethylene-s-triazine, R ₁ = allyl, R ₂ = H)

N, N'-bis (2,4-dialloxy-s-triazine-6) -diaminodiethylenpyridine (R = diethylenpyridine, R ₁ = allyl, R ₂ = H)

N, N'-bis (2,4-dialloxy-s-triazine-6) -piperazine (R = ethylene, R ₁ = allyl, R ₂ = methylene)

The process of presenting these co-agents is surprisingly simple. It is sufficient to Pooling of pure starting materials in an equimolar ratio at room temperature for several hours and allowed to stand, in general, preferably between 20 and 5O ⁰ C. In a solvent can usually be omitted. Heating or cooling operations are usually just as unnecessary as post-purification by recrystallization, since the reaction products are mostly analytically pure and are obtained as solids in a yield of approx. 80 to 98%.

In the method designed according to the invention can

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40 9 836/0939

commercial polyethylene, which is produced either by the high pressure or the low pressure process, but also mixtures of high and low pressure polyethylenes in any mixing ratio and peroxidic crosslinkable copolymers of ethylene are used. It is recommended, especially for electrical cables in the middle and high-voltage range polyethylene that is free of components that are not soluble in polyethylene, such as catalyst residues and polymerization regulators, but are also free from dust, gels and moisture. It is against it possible to work with polyethylene mixtures for low-voltage cables, which are provided with fillers, pigments, etc. are.

The organic radical formers causing the crosslinking are preferably di-tertiary alkyl or aralkyl peroxides, such as di-tertiary butyl peroxide, dicumyl peroxide, 1,3 bis (tert. butylperoxyisopropyl) benzene, 2.5 dimethyl-2.5 di (tert-butylperoxy) hexane, 2.5 dimethyl-2.5 di (tert-butylperoxy) hexyne is used in amounts of 0.1 to 5% by weight.

For mixing the polyethylene with the peroxidic crosslinking agent and the crosslinking-enhancing coagents and with stabilizers against thermal-oxidative degradation and, optionally with the addition of color pigments, a wide variety of customary mixing processes can be used. It however, it is advisable to then heat this mixture by heating it above the softening point of the polymer by means of a suitable Homogenize the kneading process, taking care that no crosslinking of the peroxide-containing mixture takes place. Instead, the polymer alone can be heated above the softening point and then the melted polymer to achieve an even distribution the additives, such as crosslinking agents, crosslinking-enhancing coagents, Color pigments and anti-aging agents are added, it being advisable to use the crosslinking agent last admit. - 13 _-

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However, in order to achieve the best possible and uniform distribution of the peroxide and that to be used according to the invention To achieve crosslinking-enhancing coagents or the mixture of such crosslinking-enhancing coagents, whereby the bubble-free, pressureless crosslinking is favored, it is advantageous to dissolve the peroxide in a suitable solvent, such as acetone, dichloromethane, benzene or alcohol to add the polyethylene present in granulate or powder form, and even before the crosslinkable polyethylene compound is processed in the extruder. To support the distribution, the mixture can be heated above the softening point of the polyethylene are homogenized. The peroxide dissolved in a solvent and optionally also the crosslinking-enhancing one Coagens can also be added directly to the molten polyethylene. In the course of meddling of the crosslinker and the crosslinking-enhancing coagent can also contain other additives, such as oxidation stabilizers, stabilizers against the copper-catalyzed degradation of polyethylene or color pigments are mixed in.

It is particularly advantageous to use a lubricant such as silicone oil or a lubricant that simultaneously serves as a solvent for the peroxide and optionally for the coagent and that which is present in granulate or powder form Polyethylene is added. Solvents such as diphenyl ether and chlorinated are used for this Biphenyl in question, which is in the processing temperature range of the polyethylene are non-volatile and do not adversely affect the crosslinking of the polyethylene.

The crosslinkable Polyäthylenmischung prepared by any of the methods described above is applied by extrusion on the freed from dust, wire drawing oil, and of optionally present on the surface oxidation products conductor and then in a liquid at temperatures above 150 ⁰ C, preferably 200-280 ⁰ C continuously depressurised networked. As a heat exchange medium, for example, polyethylene glycols, but preferably eutectic salt mixtures,

409836/0939 - 14 -

be used. Because it is easy to wash off with water, a eutectic salt mixture of 53 % potassium nitrate (KNO,), 40 % sodium nitrite (NaNO ₂ ) and 7 % sodium nitrate (NaNO,) has proven to be particularly effective as a heat exchange medium.

It is recommended that the metallic surface, for example the conductor, be heated to temperatures using a suitable preheating device before the crosslinkable polyethylene compound is applied
to preheat.

Temperatures from 80 to 200 ⁰ C, preferably from 100 to 170 ° C,

The invention is explained in more detail below with the aid of a few examples.

example 1

One made of several wires, cleaned of dust and wire drawing oil

2 built-up copper conductor with a cross-section of 1.5 mm was preheated to 120 ° C by a suitable wire preheating device and continuously with a mixture of 96.5 parts of high-pressure polyethylene (d = 0.918, melt flow index. MFI ₁ Q ₀ Z ₂ = 0.2) , 1.2 parts of 1,3-bis (tert-butylperoxyisopropyl) benzene (96 # ig), 2.0 parts of 2,4-dialloxy-6-stearylamino-s-triazine and 0.3 parts of polymeric 2.2.4-trimethyl-1,2-dihydroquinoline were spray-coated. To prepare the mixture, a solution of the peroxide, 2,4-dienoxy ~ 6-stearylamino-s-trjazins and the anti-aging agent in dichloromethane was added to the polyethylene in granulate form, the mixture was left to stand for several days and then the solvent was evaporated. The mixture was made over a:
eggs and then granulated.

The mixture was homogenized in a mixing extruder at 120 ° C

The insulation obtained with this mixture by extrusion at a melt temperature of 126-131 ° C (insulation wall thickness 0.8 mm) were then continuously through a salt bath set up next to the extruder from a eutectic nitrite-nitrate mixture at the following salt bath temperatures and dwell time "A", fial ^ iaarfU crosslinked without pressure.

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ΑΠ9836 / 0939

Salt bath temperature

VPA
- 15 -

Table 1

Salt bath residence time = crosslinking time

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Percentage networking

200 220 240 250

32

12th

81 80 83 81

After cooling via a step cooling (80, 60, 20 ⁰ C water temperature) bubble-free, although on the copper conductor
firmly adhering, but easily strippable insulation made of cross-linked * polyethylene.

The percentage crosslinking values determined as a measure of the degree of crosslinking of the crosslinked polyethylene insulation are shown in the table. By appropriate measurements of the mechanical properties of such pressureless crosslinked insulation from crosslinked! Polyethylene was able to determine that with a percentage crosslinking of 76 % and higher, the insulation is technically sufficiently crosslinked, ie the insulation produced according to Table 1 is sufficiently crosslinked.

The percentage networking is determined as follows:

Approximately 0.5 g of the crosslinked insulation are in the form of test specimens extracted with a diameter of approx. 1 mm in stabilized xylene for 6 hours and then dried in vacuo at 100 ° C. for 12 hours.

Percentage networking =

Weight of the extracted,

dried sample __ χ 100

Weight of the original sample

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409836/0939

- 16 Example 2

According to Example 1, at the crosslinking temperatures and times given there according to Table 1 Isolations made from a mixture containing triallyl cyanurate instead of 2.4-dialloxy-6-stearylamino-s-triazine contained.

In contrast to Example 1, the pressureless crosslinked insulation obtained with this mixture contained, in particular at the copper-conductor-insulation boundary layer, bubbles. They also showed samples taken at various points of the insulation Samples with different degrees of crosslinking.

Example 3

According to Example 1, a mixture was prepared which, instead of 2,4-dialloxy-6-stearylamino-s-triazine, contained a 2 parts coagent which was obtained by reacting 1 mol of triallyl cyanurate with 1 mol of a mixture of primary fatty amines (chain distribution C ₁₂ ~ ^c p ₀ ) had been received.

With this mixture by extruding at a Massetempertur 125-130 ⁰ C insulations obtained (insulation wall thickness 2.2 mm copper conductor with a cross-section of 1.5 mm ^ were then continuously by a subsequently notified to the extruder salt bath of a eutectic nitrite-nitrate mixture at the following salt bath temperatures and dwell times in the salt bath cross-linked without pressure:

Table 2

Salt bath salt bath dwell time Percentage temperature = crosslinking time crosslinking

I. ° C 1 fsecj [% J

210 18 87

230 10 87

250 7 09

260 4 86 - 17 -

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After cooling down via a step cooling (80, 60, 20 ° C water temperature) became bubble-free, cross-linked insulation that adheres firmly to the copper conductor but can be stripped off easily Obtained polyethylene with a high degree of crosslinking (Table 2).

Example 4

A carefully cleaned one made up of individual wires

2 aluminum conductors with a cross-section of 1.5 mm were preheated to 160 ° C. by a suitable wire preheater and continuously with a mixture of 96.5 parts of high-pressure polyethylene (d = 0.918, MFI ₁₉₀ Z ₂ = 0.2), 1.2 parts of 1.3 bis (Tert-butylperoxyisopropyl) benzene (96%), 2.0 parts of N, N! -Bis- (2.4-dialloxy-s-triazine-6) diaminooctane and 0.3 part of polymeric 2.2.4-trimethyl-1.2 dihydroquinoline were spray-coated .

To prepare the mixture, a solution of the peroxide, the N, N ^l -bis- (2,4-dialloxy-s-triazine-6) diaminooctane and the anti-aging agent in dichloromethane was added to the polyethylene in granulate form, the mixture was left to stand for several days and then the solvent evaporated. The mixture was homogenized through a mixing extruder at 120 ⁰ C and then granulated.

With this mixture by extruding at a material temperature 127-132 ⁰ C insulation obtained with an insulation wall thickness of 0.8 mm were then continuously depressurised by a subsequently notified to the extruder salt bath of a eutectic nitrite-nitrate mixture at the following salt bath temperatures and residence times in the salt bath networked

Table 3

Salt bath salt bath dwell time as a percentage temperature = crosslinking time crosslinking

210 15 85

220 12 86

240 9 88

250 7 87. _18th

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After cooling, bubble-free, strippable insulation that adhered well to the aluminum conductor was produced with the insulation shown in the table given crosslinking values are obtained.

Example 5

A copper conductor pretreated as in Example 1 was stabilized with a mixture of 96.3 parts of high-pressure polyethylene (d = 0.920, MFI ₁ QQy ₂ = O ^), with 0.15 percent by weight of 4,4'-thiobis- (3methyl-6-tert. butylphenol), 1.5 parts of dicumyl peroxide (95%), 2.0 parts of 2,4-dialloxy-6-stearylamino-s-triazine, 0.2 part of polymeric 2.2.4-trimethyl-1,2-dihydroquinoline. The polyethylene mixture was prepared in the manner indicated in Example 1.

The insulation obtained with this mixture by extrusion at a melt temperature of 128 - 132 ° C (insulation wall thickness 0.8 mm) were then continuously from a salt bath set up next to the extruder eutectic nitrite-nitrate mixture at the following salt bath temperatures and dwell times in the salt bath crosslinked without pressure.

Table 4 Percentage
Networking
L% 1 Salt bath
temperature
I ⁰ C 3 Salt bath residence time
= Networking time
fsecl 81
83
84
82
80 190
200
220
240
250 52
28
11
6th
4th

After cooling through a step cooling, bubble-free, firmly adhering insulations made of cross-linked to the conductor Obtained polyethylene with the crosslinking data given in the table.

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- 19 Example 6

In accordance with the information in Example 1, a mixture was prepared which instead of 1.2 parts of 1,3-bis (tert-butylperoxyisopropyl) benzene 1.6 parts of di-tert-butyl peroxide contained.

The insulation obtained with this mixture by extruding at a material temperature of 130-135 ⁰ C (Insulating wall thickness 0.8 mm copper conductor 1.5 mm) were then continuously by a subsequently notified to the extruder salt bath of a eutectic nitrite-nitrate mixture at the following salt bath temperatures and dwell times in the salt bath cross-linked without pressure:

Table 5

Salt bath salt bath dwell time Percentage temperature = crosslinking time crosslinking [ ⁰ Cj Γ see! Γ.% 1

190 72 85

210 18 86

230 10 87

250 6 84

After cooling by means of a cooling step, the insulation was bubble-free, easily strippable and with a high degree of crosslinking (Table 5).

Example 7

According to Example 1, a mixture was prepared which, instead of a high-pressure polyethylene with an MFI value of 0.2 Contained high pressure polyethylene (d = 0.918) with an MFI value of 0.5.

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The insulations obtained with this mixture according to Example 1 were free of bubbles and as in Table 6 shows very well connected.

Table 6 Percentage Salt bath Salt bath residence time Networking temperature = Networking time LO C ° c] £ secj | 79 200 32 78 220 12th 81 240 8th 80 260 4th Example 8

A carefully cleaned copper conductor according to Example 1 was heated by a suitable Drahtvorwärmeeinrichtung to 16O ° C and continuously with a mixture of 95.8 parts of high-pressure polyethylene (d = 0.918, MFI _190/2 = 0.2), 1.4 parts of 1.3-bis (Tert-butylperoxyisopropyl) benzene (96%), 2.0 parts of 2,4-dialloxy-6-dodecylamino-s-triazine, 0.3 part of polymeric 2.2.4-trimethyl-1,2-dihydroquinoline and 0.5 part of a commercially available metal deactivator encapsulated. The present granular polyethylene was mixed with the metal deactivator and homogenized a heated kneader at 180 ⁰ C under nitrogen to form the mixture. The mixture was crushed and mixed with a solution of the peroxide, the 2,4-dialloxy-6-dodecylamino-s-triazine and the anti-aging agent in dichloromethane, the mixture was left to stand for several days and then the solvent was evaporated.

The insulation obtained with this mixture by extrusion at a melt temperature of 123 - 127 ° C (insulation

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409 836/0939

Wall thickness 0.8 now) were then continuously through a salt bath made of a eutectic nitrite-nitrate mixture and placed next to the extruder at the following salt bath temperatures and dwell times in the salt bath networked without pressure:

Table 7

Salt bath Salt bath residence time Percentage temperature = Networking time Networking [ ⁰ O Γ see "] 200 40 80 220 15th 81 240 8th 79 250 6th 80

After cooling via a cooling stages (80, 60, 20 ⁰ C water temperature) were bubble-free, firmly adhering to the copper conductor, get well Strippable insulation with sufficient crosslinking times (Table 7).

Example 9

In a further series of tests, the mixture according to Example 1 was mixed with color concentrates of the colors yellow, green, brown and blue, each containing small amounts of titanium dioxide, before extrusion. The insulations obtained by extrusion with subsequent continuous pressureless crosslinking in the salt bath (crosslinking temperatures and times according to Example 1) were free of bubbles and sufficiently crosslinked. Further characterized in that the colors are not affected by the pressureless cross-linking in the salt bath at temperatures above 200 ⁰ C was found.

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409836/0939

Example 10

To prepare the core a medium voltage cable constructed of a single wire copper conductor was coated with a cross-section of 25 mm to about 120 ⁰ C preheated and wrapped in a Doppelspritzkppf simultaneously with the conductor smoothing and the insulation. A copolymer of ethylene-vinyl acrylate or ethylene-vinyl acetate was used to smooth the conductors, to which carbon black and 1 - 2 % dicumyl peroxide were added as a crosslinking agent.

The mixture described in Example 1 was used for the isolation. To produce the mixture, also proceed as described in example 1.

The extrusion of the conductor smoothing took place at a melt temperature of 110 ⁰ C, that of the insulating mixture at a melt temperature of 130 ⁰ C. Die. Insulation wall thickness was 5.5 mm. The crosslinking took place in a salt bath at 230 ° C. for 50 seconds. After cooling via a cooling stages (80, 60, 20 ⁰ C water temperature) a bubble-free, firmly adhering on the conductor smoothing also crosslinked polyethylene insulation made of crosslinked with a crosslinking percentage of 85% was obtained.

7 claims

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Claims (7)

Claims 1. A process for the production of elongated material such as shaped profiles or pipes, optionally located on a carrier, on the basis of cross-linked polyethylene, in particular for the production of electrical cables and lines with a sheath and / or with an insulation based on a cross-linked polyethylene, in which the polyethylene is extruded in the uncrosslinked state and then crosslinked under the action of heat in the presence of organic radical formers, characterized by the use of 0.1 to 20 percent by weight, based on the polymer, of a crosslinking-enhancing coagent based on 2,4-dienoxy-6-amino-alkyl {en) -s-triazines and / or of N, N'- Bis- (2,4-dienoxy-s-triazine-6) -diamines containing polyethylene mixture, which after extrusion by heating in a heating section, for example in a salt bath, a liquid bath, a fluidized bed or in hot air or in a correspondingly heated Inert gas such as nitrogen, argon, carbon dioxide, etc. at or approximately at atmospheric pressure and at a temperature of over 150 ⁰ C, preferably of at least 200 ⁰ C, is continuously crosslinked. 2. The method according to claim 1, characterized in that the organic radical formers required for crosslinking as well as the crosslinking-enhancing co-agent, the polyethylene, which is in powder or granulate form, before it is introduced of the polyethylene added as a solution in the extruder and mixed with the polyethylene. - 24 - 409836/0939 3. The method according to claim 2, characterized in that the polyethylene present in powder or granulate form a liquid lubricant, possibly insoluble in polyethylene, such as silicone oil or polyglycol in an amount of 0.05 - 1.0 96, preferably 0.2 - 0.5% » is outwardly drummed up. 4. The method according to claim 2, characterized in that the polyethylene present in powder or granule form a non-volatile in the range of the processing temperature of the polyethylene, not the later crosslinking process disadvantageously influencing solvents such as diphenyl ether or chlorinated diphenyl are added. 5. The method according to any one of claims 1 to 4, characterized in that that the polyethylene mixture 0.1-5 wt .- $ 6, based on the weight of the polymer, of the crosslinking reinforcing Contains coagens. 6. The method according to any one of claims 1 to 5, characterized in that that as a crosslinking-enhancing coagent 2,4-dialkenoxy-6-alkyl (-en) amino-s-triazines of the general formula «3 be used in which R is an allyl, methallyl, ethallyl, propallyl, 3-ethyl-butenyl-2-, 3-butenyl, 2,4-hexadienyl, Crotyl, 3-nonenyl and - 25th 409836/0939 73/7532 R ^ = R, but also the groups described under R. in various combinations to R-. can stand, and Rp is an alkyl group with 1 to 20 carbon atoms, an alkyleneycloalkane group with k to 10 carbon atoms, an alkylenaryl (-heteroaryl) group with 7 to 10 carbon atoms, mean an allyl, alkene and alkyne group having 3 to 16 carbon atoms and R_ = hydrogen or an alkylene group, which can be cyclically linked to Rp, individual methylene groups being substituted by oxy or thio groups could be. 7. The method according to any one of claims 1 to 5, characterized in that as a crosslinking-enhancing coagent bridged unsaturated s-triazines of the general formula R ₄ O be used in which R is an alkylene group with 2 to 18 carbon atoms, a bisalkylenecycloalkane group with 5-10 carbon atoms, or dialkylenefuran, thiophene, pyridine or triazine group with 6 to 12 carbon atoms and other heterocycles which are polysubstituted by alkylene groups, - 26 409836/0939 preferably allyl, but also crotyl, methallyl-ethallyl, Propallyl, 3-butenyl, 2-hexenyl, 2,4-hexadienyl-3-decenyl and other unsaturated groups mean and s can be H or an alkylene group, which together with R forms a diazacycloaliphatic ring. 409836/0939